UCLA UCLA Electronic Theses and Dissertations Title Community-dependent Positive Interactions in Southern California Coastal Ecosystems Permalink https://escholarship.org/uc/item/1vn6w0f6 Author Bryson, Sarah Publication Date 2012 Peer reviewed|Thesis/dissertation eScholarship.org Powered by the California Digital Library University of California UNIVERSITY OF CALIFORNIA Los Angeles Community-dependent Positive Interactions in Southern California Coastal Ecosystems A dissertation submitted in partial satisfaction of the requirements for the degree Doctor of Philosophy in Biology by Sarah Bryson 2012 ABSTRACT OF THE DISSERTATION Community-dependent Positive Interactions in Southern California Coastal Ecosystems by Sarah Bryson Doctor of Philosophy in Biology University of California, Los Angeles, 2012 Professor Peggy Fong, Co-chair Professor Richard R. Vance, Co-chair Ecological interactions are context dependent. The net effect of species interactions includes the multifaceted impacts of community composition and abiotic influences of the environment. I examined how both biotic and abiotic stressors, in the form of herbivore composition and salinity stress, respectively, elicited positive interactions between species. In a kelp forest I examined how the relationship between kelp and an encrusting bryozoan, Membranipora membranacea , shifted to an associational defense depending on herbivore guild composition. Using a combination of choice experiments and surveys of grazing damage, I demonstrated that the mesograzers Lacuna unifasciata , Perampithoe humeralis , and Idotea resecata almost entirely avoided (<1% of total diet) encrusted kelp. The large snail Norrisia norrisi also preferred clean ii kelp, but kelp crabs, Pugettia producta , targeted encrusted kelp. Field surveys in a mesograzer dominated canopy found 2.5 times more grazing damage on sparsely encrusted kelp than on heavily encrusted kelp and far more grazing in the upper canopy than on the blades from the vertical stipes below the canopy. These results indicate that, when mesograzers are dominant, Membranipora provides kelp associational resistance to grazing. Such protection may be more prominent in the upper canopy. Additionally, I examined the role of abiotic stress on positive interactions in a hypersaline salt marsh. Following disturbance that removes established vegetation, salt-tolerant species can ameliorate harsh soil salinities for less tolerant species and therefore promote secondary succession. However, when abiotic stress is extremely high amelioration may be inadequate to improve growth of associated neighbors. Using clipping manipulations of Batis maritima , an early successional halophyte, I tested whether B.maritima facilitates secondary succession in an excessively hypersaline salt marsh in southern California. Experimental plots with B.maritima present recovered faster (27% compared to 14% revegetation by matrix species) and had lower increases in soil salinity. Salicornia pacifica and Arthrocnemum subterminale were the dominant recovery species in both treatments and no differences were found in species richness, diversity, or evenness of recovery species between treatments. Overall, my research indicates positive interactions play a prominent role in these coastal ecosystems though that role will depend on the specific nature of the community. iii The dissertation of Sarah Bryson is approved. Richard F. Ambrose Cheryl Ann Zimmer Richard R. Vance, Committee Co-Chair Peggy Fong, Committee Co-Chair University of California, Los Angeles 2012 iv TABLE OF CONTENTS ABSTRACT…………………………………..……………………………………………..…..ii COMMITTEE APPROVAL…………………………………………………………………....iv TABLE OF CONTENTS………………………………………………………………………..v LIST OF FIGURES……...……………………………………………………………………...vi LISTS OF TABLES…………………………………..………………………………………..vii ACKNOWLEDGEMENTS…………………..………………………………………………..viii VITA……………………………………………..……………………………………………...xi Introduction ………………………………………………………………………………….….1 Introduction references……………………………………………………….….5 I. Community-dependent associational resistance in a kelp canopy …………………..8 References..……………………………………………………………………..24 II. Mesograzer abundance and grazing damage in a giant kelp forest canopy ………30 References………………………………………………………………………46 III. Facilitation of secondary succession in an ultrahypersaline salt marsh in southern California ............................................................................................51 References………………………………………………………………………68 Conclusions…………………………………………………………………………………….72 Conclusion references…………………………………………………………..75 v LIST OF FIGURES Chapter 1 Community-dependent associational resistance in a kelp canopy Fig. 1 Example of experimental kelp for small grazers…………………….……….20 Fig. 2 Preference for encrusted or unencrusted kelp of the five grazers..…...………21 Fig. 3 Area grazed on sparse and dense sides of kelp blades collected during field sampling ……………………………………………………………...22 Chapter 2 Mesograzer abundance and grazing damage in a giant kelp forest canopy Fig. 1 Membranipora membranacea colonies on a kelp blade.……………………..43 Fig. 2 Abundance of amphipods and Idotea resecata collected from two depth strata within the kelp canopy………………………………………………..44 Fig. 3 Differences in grazing scar counts per blade between depth strata…………..45 Chapter 3 Facilitation of secondary succession in an ultrahypersaline salt marsh in southern California Fig. 1 Location and close-up of Mugu Lagoon in southern California.……………..63 Fig. 2 Percent of total vegetation cover of each species present prior to clearing…..64 Fig. 3 Percent cover of vegetation at final sampling for matrix vegetation and B.maritima alone ………………………………...…………………...65 Fig. 4 Soil salinity differences between B. maritima present and clipped treatments.… ………………………………………...………………66 Fig. 5 Final species composition.……………………………………………...…….67 vi LIST OF TABLES Chapter 1 Community-dependent associational resistance in a kelp canopy Table 1 Specifications from preferences assays ….………………….………23 vii ACKNOWLEDGMENTS This work was funded by awards from the University of California Natural Reserve System Mildred E. Mathias Graduate Student Research Grant Program, Sigma Xi Grant- in-aid of Research Program, and research grants from the Department of Ecology and Evolutionary Biology at UCLA. I received fellowship support from the Eugene Cota-Robles program through the Graduate Division at UCLA and from the Department of Ecology and Evolutionary Biology at UCLA. Without such support this research could not have been completed. I am deeply grateful for the tireless support of my advisor Peggy Fong. She has been a source of encouragement, collaboration, and resourcefulness throughout this process. I could not have completed this research without her efforts. I am also grateful for the advice and the willingness to serve as a sounding board for my studies from my co-advisor Rick Vance. I received additional support, constructive advice, and editorial revisions from my committee members Cheryl Ann Zimmer and Rich Ambrose, which has been incredibly helpful in this process. I would like to acknowledge the tremendous support I received from my lab members, who provided field assistance, intellectual engagement, and constructive critiques of my projects. I am particularly grateful to Lauri Green, who was an always willing dive and field assistant. I am also indebted to the efforts of many undergraduate assistants, the Fong family, and Carrie Chasteen for field assistance and sample processing. Most notably, Elizabeth Shimer, Sarah Hogan, and Sarah Joy Bittick provided extensive assistance in the field and with project design. viii This project could not have been completed without the access to field sites and equipment that I was given. I want to thank the Bodega Marine Lab for use of their marine lab facilities. I also want to thank Linda Chilton and the Cabrillo Aquarium for giving me space and access to equipment and resources to conduct this research. I am greatly appreciative of King Harbor Marina in Redondo Beach, California for boat slip use. And, I am utterly indebted to Martin Ruane of the US Navy Environmental Division for allowing my access to field sites at Mugu Lagoon. My close friends and family have endured the completion of this research. They have helped me through ridiculously hard times and have also enjoyed the fun times along side me. I am so grateful to the hoochies: Tonya Kane, Rachel Kennison, Natalia Kennedy, and Jessica Lieder for the all-important emotional support I needed. Tonya, in particular, has listened to my complaints, stayed up late with me in the lab, and offered help without being asked. I would like to say thank you to my family. My husband Hank Truxillo has read my grant proposal, listened to my analysis problems, watched the kids, and has allows been encouraging and supportive. My daughters Elena and Penny Truxillo have been so wonderfully patient while I’ve been writing behind a locked door or during long trips to field. Some times as I packed them in and packed them out. Interesting though, someone has scribbled in my lab notebook. Of course, I also thank my mother, Pam Bryson, and father, Fred Bryson, who have always listened to me and encouraged me over the years. Finally, I offer special thanks to a few people who gone above and beyond to help me through this research. Jocelyn Yamadera of the Ecology and Evolutionary Biology Department has been ix so wonderfully reliable and inventive in her solving of administrative crises while also being